<!DOCTYPE HTML>
<html>
<head>
        <meta charset="UTF-8">
        <title>My WebSocket</title>
    <script src="webjars/jquery/3.4.1/jquery.min.js"></script>
        <style>
            #message{
                    margin-top: 40px;
                    border:1px solid gray;
                    padding:20px;
                }
        </style>
</head>
<body>
昵称：<input type="text" id="name"/>
<button onclick="conectWebSocket()">连接WebSocket</button>
<button onclick="closeWebSocket()">断开连接</button>
<hr />
消息：<input id="text" type="text" />
频道号：<input id="toUser" type="text" />
<button onclick="send()">发送消息</button>
<br />
<div id="message"></div>
</body>
<script type="text/javascript">

    var websocket = null;
    function conectWebSocket(){
        var name=document.getElementById("name").value;
        //在连接之前校验一下昵称是否为空
        if(name===''){
            alert("请输入昵称");
            return;
        }
        //判断当前浏览器是否支持WebSocket
        if ('WebSocket'in window) {
            websocket = new WebSocket("ws://localhost:8080/websocket/"+name);
        } else {
            alert('Not support websocket')
        }
        //连接发生错误的回调方法
        websocket.onerror = function() {
            setMessageInnerHTML("连接错误");
        };
        //连接成功建立的回调方法
        websocket.onopen = function() {
            setMessageInnerHTML("连接成功");
        }
        //接收到消息的回调方法
        websocket.onmessage = function(event) {
            setMessageInnerHTML(event.data);
        }
        //连接关闭的回调方法
        websocket.onclose = function() {
            setMessageInnerHTML("聊天已关闭");
        }
        //监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
        window.onbeforeunload = function() {
            websocket.close();
        }
    }
    //将消息显示在网页上
    function setMessageInnerHTML(innerHTML) {
        document.getElementById('message').innerHTML += innerHTML + '<br/>';
    }
    //关闭连接
    function closeWebSocket() {
        websocket.close();
    }
    //发送消息
    function send() {
        var message = document.getElementById('text').value;
        var toUser = document.getElementById('toUser').value;
        var socketMessage;
        if(toUser==""){
            socketMessage= {msg:message,toUser:toUser,type:0};
        }else{
            socketMessage= {msg:message,toUser:toUser,type:1};//不能加“ ”
        }
        websocket.send(JSON.stringify(socketMessage));
    }
</script>
</html>
